24.5013GPPNon-Access-Stratum (NAS) protocol for 5G System (5GS)Release 17Stage 3TS
The message authentication code (MAC) information element contains the integrity protection information for the message. The MAC IE shall be included in the SECURITY PROTECTED 5GS NAS MESSAGE message if a valid 5G NAS security context exists and security functions are started.
The message authentication code (MAC) is also included in the Intra N1 mode NAS transparent container IE and in the S1 mode to N1 mode NAS transparent container IE.
The usage of MAC is specified in subclause 220.127.116.11.